Using a linearization formalism in the framework of dependency grammars, this article proposes a simple analysis of new data on word order constraints in Korean ko construction composed of three verbs V3-ko V2 V1. It will be shown that V3-ko rejoins the verb cluster in the case of extraction of its nominal dependent, while V3-ko forms an independent constituent with its dependent in the case where extraction does not take place. We show that island constraints can take place indirectly at the level of topological (constituent) structure, contrary to classic descriptions of extraction put forth by Ross (1967) or Kaplan & Zaenen (1989).